1. Field of the Invention
This invention relates to methods and apparatus for providing improved innerspring constructions for mattresses, box springs, cushions or other bedding items. Particularly, the invention relates to methods and apparatus for producing improved pocketed coil innerspring construction, which due to the orientation of individual pocketed coil strings within the innerspring construction exhibit improved physical properties. The invention also relates to innerspring constructions per se.
2. Description of Related Art
In the bedding industry, it is well known to provide mattresses having innerspring constructions. One type of innerspring construction is the "Marshall"-type, in which coil springs are pocketed within fabric to create finite lengths or "strings" of pocketed coils. The coil spring pockets may be defined by sewing transverse and longitudinal seams, or may be formed by the use of ultrasonic thermal welding as disclosed in U.S. Pat. Nos. 4,234,983 and 4,234,984 to Stumpf which are produced and incorporated herein by reference. Such strings of pocketed coils may be produced by the use of pocketing machines such as those disclosed in U.S. Pat. Nos. 4,439,977 and 4,854,023 to Stumpf which are incorporated herein by reference. Such pocketed strings may be assembled to create innerspring constructions such as shown in U.S. Pat. Nos. 4,401,501, 4,578,834 or 4,566,926, all incorporated herein by reference.
Although satisfactory innerspring constructions are provided utilizing the methods and apparatus taught in the above-referenced patents, improved methods and apparatus for producing such products are required. Particularly, a need exists to provide innerspring constructions, as well as a methods and apparatus for creating such constructions, which exhibit improved dimensional stability and structural integrity while enabling greater innerspring and mattress firmness for a particular spring wire diameter.